The gold standard techniques to stage and diagnose the mediastinum in patients with lung cancer consist of cervical mediastinoscopy (CM). CT, PET and PET-CT scans have improved the radiological staging of the mediastinum; however these techniques are unable to provide a tissue diagnosis and are inaccurate. Endobronchial ultrasound (EBUS) and endoscopic ultrasound (EUS) have been available for the past few years and are proving invaluable in the diagnosis and staging of the mediastinum. These techniques rely on imaging of mediastinal lymph nodes (LN) through the airway (EBUS) and the esophagus (EUS) using miniaturized ultrasound probes mounted on the tip of flexible bronchoscopes (EBUS) and esophagoscopes (EUS). Once a LN is visualized and identified using either of these techniques, a needle is passed through the airway (EBUS) or esophageal (EUS) wall into the LN and biopsies are performed. These minimally invasive trans-luminal techniques do not require general anesthesia and can be performed safely, rapidly, accurately and at low cost.